1. Field of the Invention
This invention relates to non-contact surface mensuration methods and apparatus which provide data to digital computers and more particularly apparatus capable of high data rates so that movement of the surface, such as occurs with live subjects, can be accommodated.
2. The Prior Art
Surface mensuration apparatus have been limited to use on inanimate subjects because of methods that are inherently slow. Examples are U.S. Pat. Nos. 4,089,608 and 4,373,804 which use mechanical scanning or mechanical error correction. To make a high resolution measurement of the surface of a living subject, such as the human head, measurement rates greater than 10,000 points per second are required. At these high rates image data can be collected before movement of the subject causes excessive distortion in the image.
A second problem with optical non-contact apparatus is shadowing of the light beam or obstruction of the sensor's view by features of the subject surface. U.S. Pat. No. 4,089,608 is an example which has this limitation.